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Existing design guidelines for concrete hinges are focusing on serviceability limit states. Lack of knowledge about ultimate limit states was the motivation for this work. Experimental data are taken from a testing series on reinforced concrete hinges subjected to eccentric compression up to their bearing capacity. These tests are simulated using the finite element (FE) software Atena science and a material model for concrete implemented therein. The first simulation is based on default input derived from measured values of Young's modulus and of the cube compressive strength of the concrete. The numerical results overestimate the initial stiffness and the bearing capacity of the tested concrete hinges. Therefore, it is concluded that concrete was damaged already before the tests. A multiscale model for tensile failure of concrete is used to correlate the preexisting damage to corresponding values of Young's modulus, the tensile strength, and the fracture energy of concrete. This allows for identifying the preexisting damage in the context of correlated structural sensitivity analyses, such that the simulated initial stiffness agrees well with experimental data. In order to simulate the bearing capacity adequately, the triaxial compressive strength of concrete is reduced to a level that is consistent with regulations according to Eurocode 2. Corresponding FE simulations suggest that the ductile structural failure of concrete hinges results from the ductile material failure of concrete at the surface of the compressed lateral notch. Finally, Eurocode-inspired interaction envelopes for concrete hinges subjected to compression and bending are derived. They agree well with the experimental data.

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Many post-tensioned girders of existing bridges contain a low amount of transverse reinforcement. The shear strength of these girders, calculated according to current semi-probabilistic design codes, like Eurocode 2, is often less than that required in the codes. In this paper, the experimental results of four shear tests on post-tensioned bridge girders of existing bridges are presented. The specimens were extracted from two different road bridges, both built in 1959. In this paper, the results of this test series are used to analyze the shear behavior and failure modes of existing post-tensioned bridge structures with a low amount of shear reinforcement. Furthermore, the experimental results are compared with the shear strengths calculated according to various design codes. Finally, the shear behavior is analyzed according to the zone-based, shear assessment concept with its refined shear models. The calculation results agree well with the data from the experiments.

Temperatureinwirkungen sind für die wirtschaftliche Dimensionierung von Lager‐ und Fahrbahnübergangskonstruktionen sehr relevant. Zusätzlich führen größere Bemessungseinwirkungen, die zufolge Temperatur entstehen, auch bei integralen Brücken zu einer Erhöhung der Zwangsbeanspruchung. Die Entwicklung möglichst realistischer Temperaturansätze ist daher von großer technischer und wirtschaftlicher Bedeutung. Im Rahmen des Projekts „Modifiziertes Temperaturlastmodell für Eisenbahnbrücken (MTE 2.0)“, das von den Österreichischen Bundesbahnen initiiert wurde, konnten an sechs Massivbrücken Langzeittemperatur‐ und Verformungsmessungen durchgeführt werden. Zusätzlich erfolgten numerische instationäre Simulationen und Vergleichsrechnungen zur Untersuchung der thermischen Beanspruchungen, des Temperaturgradienten sowie zeitabhängiger Effekte (Kriechen, Schwinden). Schließlich wurden Temperaturdaten der Österreichischen Zentralanstalt für Meteorologie und Geodynamik (ZAMG) probabilistisch analysiert, um die Korrelation zwischen maximaler Außenlufttemperatur und konstantem Temperaturanteil für Brücken zu optimieren. Anhand dieser Langzeitmessungen, Simulationen und Analysen konnte die Basis für ein optimiertes Temperaturlastmodell für Massivbrücken geschaffen werden, das vor allem bei Tragwerken mit geringer Schlankheit und massigen Querschnitten von großer Bedeutung ist und wirtschaftliche Vorteile im Entwurf bringt, ohne die Zuverlässigkeit der Konstruktion negativ zu beeinflussen.